January 2011 Archive

We took the Kitefoiler out again today to see how it performed after we had fixed the rubbing issue from yesterday. The boat consistently foiled on the starboard side, but required much more manual adjustment to foil on the port side. This suggested that the foils were asymmetrical, which we later verified through measurement. We also learned that the actual pivot point location was not where we expected it to be, which was preventing the sensors from controlling the J-foil angle of attack, as intended. We shaved some material off the J-foil extensions to address this issue and hope to see better results tomorrow.

The force required to pull the kitefoiler were a bit higher in these tests due to […more]

Today we performed a second tow test of the new kitefoiler. Some minor repairs had been made since the last test, the sensors and foils were adjusted, and the tiller was strengthened. The boat now weighs in at 390 lbs, which is a larger increase than expected. It is possible that we under-measured the kitefoiler weight before the first test.

This time Don manned the helm. We were able to get the boat more stably onto its foils, especially after Dudu and Joe began to adjust the foil angles manually. We found that there was interference from the bottom of the cassette fairing. We will make a mod in the morning and be back out there tow testing first thing.

Today the kitefoiler was put into the water for the first time. It floated well and we were able to get a sense for its handling while recording load and speed data. The boat got up onto its front foils at around 16 knots, which required approximately 150 kgf of tension on the line. As the boat came out of the water, the force required to pull it diminished. Once up on the foils there were a few problems, so each towing run ended quickly.

The boat’s weight, measured just before launch, was 355 lbs.

The first graph shows the line tension and boat speed vs. time. There are 8 distinct episodes in which the boat is towed, and as […more]